The present invention, in some embodiments thereof, relates to the generation and emission of radiation, and, more particularly, but not exclusively, to generation and emission of Terahertz (THz) radiation by inducing and exploiting the coherence of electronic states.
Terahertz radiation has been produced hitherto by applying ultra-short laser pulses to biased dielectric material. Terahertz radiation pulses are generated by allowing a short laser pulse to be incident on the gap between a pair of charged strip lines separated by a semiconductor such as semi-insulating GaAs. If the wavelength of the laser light is above the band-gap of the GaAs, electron-hole pairs are generated which create a conducting path between the two lines, allowing current to flow. The sudden rise in the current between the conductors causes a large amount of radiation to be given off, caused by the sudden acceleration of the photo-generated carriers by the strong electric which exists in the gap region.
Examples of known arrangements for generating THz radiation are found in U.S. Pat. Nos. 7,974,325, 7,498,593, U.S. Published Application No. 20060076518, and European Patent Publication No. EP200606776.